The purpose of this project is to characterize the phenotype and genotype of a kindred wiht renal Mg Wasting. We will perform systematic genome scans in order to positionally clone the gene responsible for this disorder. The phenotype of the affected members will also be assessed. These data will provide important information about Mg transport as well as providing a tool by which to study regulation of Mg transport by hormones, growth factors, and pharmaceutical agent The phenotypic finding will allow us to identify complications of depleted Mg.